There is only one “identically designed” (in a manner of speaking) alternative to the P-37d that I know of, and I have posted detailed comparisons of it and the P-32d, which you can find by searching here for “faux Yamaha.” That one is very cheaply constructed, has inferior reeds, and doesn’t sound anything like the real Yamaha. There are also some other pianicas advertised as Yamahas on eBay. They are not and do not sound the same. The only current true Yamahas bear the designation P-37, P-32, or P-25. There are many similar looking melodicas under various names, most cheap, some expensive. Hearing a few arpeggios played gives a general idea of the type of sound but not of all the different nuances of sound a skilled player (and even to some extent a beginner) can get from one melodica but not from another. For someone who wants the sound and feel of a Yamaha, there is no substitute. And they are well worth what they cost.